Down-hole cables are found in use in many industries including those that conduct deep drilling, such as within the oil drilling industry. These cables may be used to transmit information and data from a drilling region having the drilling equipment to a control center located remote to the drilling region. Many oil-drilling regions are located deep within the Earth's crust, such as those seen with onshore and offshore drilling. The drilling region may be 5,000 feet or more from a control center located on the Earth's surface or a control center located on water at sea level. A cable of 5,000 feet or more may have a high weight that, when located vertically down a drilling hole, distorts the structure of the cable itself. This may result in a failure of the cable or a deformity of the cable that renders it more inefficient than a non-deformed cable.
Current cables include a filler constructed from solid polypropylene that surrounds a conductor and enclosed with an armored sheath, such as a superalloy like Incoloy or a stainless steel. The purpose of the polypropylene filler is to provide a compressive force between the conductor core and the armored sheath, thereby producing a force to retain the conductor core within the cable. The force produced by the solid polypropylene filler may counteract a pullout force, which is the force necessary to remove the conductor core from the cable. The polypropylene fillers that are used are rated at 150° C. and therefore are frequently unable to retain their integrity when the cable is being produced using a heated method. This is due to the inherent crystallinity of the extruded polypropylene filler and the after effect of additional heat cycles from the encapsulation extrusion of the armored sheath. These additional heat cycles cause a phase shift in the polypropylene, which, in effect, reduce the diameter of the material, which lessens the pullout force necessary to compromise the cable. The encapsulation extrusion process has temperatures that are greater than the annealing temperature of the polypropylene facilitating the phase shift. This results in a cable that may easily be damaged from its own weight creating a pullout force on the conductor core resulting in the conductor core moving within the cable.
Thus, a heretofore unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies.